Retroactive Image Search Using k-d Tree

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Solution Overview

Problem

Social networking systems face challenges in efficiently identifying and removing undesirable content, such as pornographic, hateful, or violent images, from their vast databases, as existing methods are inefficient and require frequent manual updates of blacklists.

Innovation Solution

Implementing a k-dimensional tree (k-d tree) data structure to store images, combined with an image-matching algorithm like PhotoDNA, which generates hashes for content comparison, allowing for efficient retroactive searches and updates by focusing on the delta blacklist, thereby improving search performance and scalability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional linear search methods are used to identify undesirable content in image databases, then the search can be performed on all images, but the search efficiency and time consumption deteriorate significantly as database size increases

Engineering Contradiction:
Improvecontent identification accuracyVSAvoidsearch time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent segments the image database into multiple clusters using k-means clustering, where each cluster represents a group of similar images. This segmentation allows the search algorithm to focus on relevant clusters rather than scanning the entire database, significantly reducing search time while maintaining identification accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transforms the search problem from a linear one-dimensional approach to a multi-dimensional space using k-d trees. By organizing images in k-dimensional space based on their feature vectors, the system enables efficient multidimensional range queries and nearest neighbor searches, dramatically improving search efficiency for large databases.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If manual blacklist updates are performed frequently to maintain content safety, then the system can respond to new undesirable content, but the operational complexity and resource consumption increase

Engineering Contradiction:
Improvecontent safetyVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a semi-automated system where the k-d tree structure automatically organizes and searches image databases based on updated blacklist criteria. The system self-adjusts by incorporating new blacklist images into the existing k-d tree structure without requiring complete manual reprocessing, reducing operational complexity while maintaining content safety.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent performs preliminary clustering and k-d tree construction on the entire image database before blacklist updates occur. When new blacklist images are added, the system only needs to perform localized updates to the existing structure rather than complete reprocessing, reducing the complexity of frequent updates while maintaining reliability.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If comprehensive image analysis is performed on all uploaded images, then content safety is improved, but the computational resources and processing time increase significantly

Engineering Contradiction:
Improvecontent safetyVSAvoidcomputational resource consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies partial analysis by focusing computational resources only on images that are likely to match undesirable content. Using the k-d tree structure, the system performs targeted searches on relevant image clusters rather than analyzing every image comprehensively, reducing energy consumption while maintaining content safety through focused detection.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent replaces exhaustive mechanical scanning of all images with an intelligent search mechanism based on k-d trees and similarity metrics. This substitution allows the system to efficiently locate potentially undesirable images through smart querying in feature space, dramatically reducing computational resource consumption compared to brute-force analysis of all images.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9053191B2Retroactive search of objects using <i>k</i>-d tree
Publication Date: 2015.06.09 META PLATFORMS INC
  • US9053191B2 patent drawing
  • US9053191B2 patent drawing
  • US9053191B2 patent drawing

AI summary

In one embodiment, a method includes at time t2, determining a delta set of first objects representing a difference between a first set of first objects at time t1 and a second set of first objects at time t2; comparing the delta set of first objects with a set of second objects represented as a balanced k-dimensional tree; and identifying each second object whose content substantially matches content of at least one first object from the delta set of first objects.